Device for use in constructing maps from aerial photographs



Sept. 6, 1949. E. .1. scHLATTER DEVICE FOR USE IN CONSTRUCTING' MAPS FROVI AERIAL PHOTOGRAPHS 2 Sheets-Sheet 1 Filed Feb. 9, 1945 DEVICE FOR USE IN CONSTRUCTING Sept 6 1949- E. J. scHLATTER 2,481,246

` MAPS FROM AERIAL PHOTOGRAPHS Filed Feb. 9, 1945 2 Sheets-Sheet 2 '2,481,24t` n `4 Y toit use in CONISTUCTING Ms FROM AERiL PHOTOGRAPHS Washington, D. v iiiitaiit rtiii?iiyv 9, 1945;' serial N6.' 57i-,09e

The invention Vherein descriied relates t trie production of maps from aerial photographs, and to the use of individual or stereoscopic' pairs of aerial photographs for laiid studies; geologi studies;'areameasurement' linear measurements, or other uses involving extraction' of data f'rinV aerial photographs.

Aerial photographs are commonly taken i'r con; se'cutive order along a more or less straight: line defined by the path df thea'irplaiieih' night.. photographs are taken atsuch intervals of time" that'each photograph overlaps the' next orie in theV line of flight by about 60%, that is;Y about 60% of the ground area shown on a photograph will appear on the next photograph; vThe photographs taken along such a flight line are commonly called a strip The flight .lines ofthe airplane are spaced laterally so that there willJoe` a small" overlap between adjacent strips; usually amounting to about 30% of the lateral dimension" o'f one picture. The photographic coverage 'f an area or a project isplann'edi in` such mannerso that it will; be possible to .determine therelati've' scale or size" between any' two overlapping photographs by comparing measured distances' between like' images o'n the photographs'. l

The methods of orienting. successive aerial photographs in correct geod'etic or geographic; position and directioni known' as" the. slotted teniplet method, the spider templet method," the analytical ray method, the analytical'mathem'at# ical method, and' the hand'templet method all' dei pendon'the accuratetransfer hypiicker-point o'r other marking means' of identable image-points selected on one photograph to those identical" points on overlapping photographs. In many cases these selected image-points must' appear within a certain limited area on the* photograph to permit use of the particular'. technical' method adopted'.` The numerous methods of;determin`. ing' the scale, the size, and'thetilt'of" individuali pl'iotographsl progressively" along' a flight strip' likewise very often depend'o' the precisetransffer of selected'im'agelpoints from one photograph to" an' overlapping one.` Again; in` most cases.; these `image-points mustvappear within' acertain limited" area on the photograph! It is a common occurrence to find'tht therear'e" no'images ofv Wellldened objects in the: area''or areas on a photographwher'an imagepoint is badly needed. For example,a"photograph shovv` ingprairie'land-may havealarge expanse without a conspicuous-driable nuage-point.''.` Areas" coveredlv by'f forest' presentfslmilar dilcultie's" as do expanses of water.

l Y'rile'.purpose oftnisipvention yist@ provide an improved.,optico-mechanical, means vfor use in oonjunctionewith either alensv stereoscop-e .or ,.a mirror-stereoscope toeecta more. precise.,trans-v fer,and...marking of, desired points f,1oinor1i e photograph .to .an oyer1apping one regardless; Q whether..ornotanimage definable by thenaked eye. .existsin Jthedcsired area The instrument is so .designed that .the point. `iderltcationand the marking may be accomplished in one opera-l tion i and. so .thatthe operatonmay at allinstants during, thepo'int transfer check the accuracy of hiswork.. ...mi .,..i i When two overlapping 4aerialL photographs are placed under a stereoscope .and ,.properly spaced and orientedarohs'enver looking into the4 stereo,- scope will perceive .the ,illusion of the so-called third .dimensioni that..is," the tops. of hills, will appear above `-the `valleys, the. tops ,oiltrees will appear. above the ground. and ,variousother .points will; appear to beatth'eir distinctive elevations.` The. observer will;vv neiect, s'ee, th-e terrain as though he weresuspe'nded in" theairup above the area;` Ian observen were .viewing'.. two overlappingphdtographs:stereoscopically andnoted a particulanpint on. the ground such' as the inter-4 secti'rf of two' sharply defined narrow paths.. he would seethat' itwas at ground level. .If hewere. totherf-temporarily remove th'e stereoscope and with a' fine D'eii put` a vsmall dot of. ink oneach photograph where the intersection appeared, and afterwardrestoreithe stereoscope and .again look through it, .he.wo uld see asmall ,.blackdot, con. sis'ting'of the fused image formed .by the two ink dots; which appear .to rest at the level ofthe ground", eiac'tlyfon' the .intersection of the paths. If the particular pointwere the. top of a flagp'ole' and' the s'arrie procedure were followed. the fused? dot would appearV to-.he exactly at' the top of th'e flagp'ol'e through the' stereoscope. Convrsely', ivf an" ohserver ldoks-st'ereoscopically at two overlpp'ig: photographs," and thenmanipulatesAV two-small" dots; 'one with. his left hand and one' wi'thhsrightv hand', until the fuseddo't as sejrthroughfth'e"sterescope'appears to rest exactly ona'dat the same levelof a particular. poititthe streoscopi area, the left-.hand dot vfil'l-be` eiiactly on" the'piriton the left picture. and' the' right-'hand dot '..will vbe eiiactlyon. the coi-respondingpoitlon the righthand picture. Furthermore, if the fused dot rests apparently. oh'thrgroundih an openv expanselwh-ere there is.- n'o' ydena'Jole image-'point'.the left-hand dotand thriglit-hand dot will been thesame point on f the two" corresponding photographs. i

The invention is designed to accomplish the accurate and rapid transfer of points from one photograph to an overlapping one and to permit the operator to actually see and check the position of the fused dot as the points are being -marked on the two photographs, that is, the points The invention, hereinafter referred to as` the stereo-marker, consists essentially of two trans-,-`

parent, rigid disks, each carrying in its approximate center a dot or other suitable mark, andhaving a needle point fastened in the under side of each disk, said'needle point to be directly beneath the mark. The disks are fastened to a round connecting bar by means of arms and sliding connectionsso that relative motion between the disks may be possible in a left-right direction,

in a forward-back direction, and in a vertical direction. In other words,- the disks have three directional movement with relation to each other. Suitable hand screws are provided to obtain fine adjustment of these motions. l

The stereo-marker will be placed on the photographs so that the two marker-disks face the observer. These disks each have a very ne needle point protruding Vfrom the lower surface. WhenV viewed from above, these needles, whose upper ends are covered with black or other distinctive colored pigment or dye or other coloring matter, appear'as small dots. Bymeans of the two vertical adjusting screws at the rear of the arms, the disks will be'raised up so vthat the needle points will be above'the'surface of the pictures, and will not catch thereon as the marker is shifted about.- The right-left distance between the disks will now be roughly adjusted to the right amount by loosening the clamp screw at the rear of the left arm and sliding the arm along the rear horizontal baruntil that distance is approximately equal to lthedistance between like images on the two pictures. Then, some particular area, in which a pointis desired will be selected. Y

The stereo-marker will be shiftedbyhand-until thetwo dots are approximately near that area. The vertical adjustment screws will then Ybe manipulated untilpztheneedlefpoints have been lowered to where theyare almost on the surface of the photographs, the clearance probably being not more than two or three hundredths of an inch. Then, while lookingV through the stereoscope, the observer -will manipulate the horizontal screw adjustment attached to the-V left disk and will simultaneously manipulate the screwA adjustment attached to the rear of the right arm, and possibly shift the whole instrument slightly until the fused dot formed bythe tops ofthe two needle-points rests at the exact level he desires and on the exact point he desires. Then, while continuously viewing the fused dot to note-that it remains in proper position he will depress the markers by pressure with his left and right thumbs on the left and rightarms, which are to ybe constructed of spring metal or other resilient material. While doing this he will hold the stereo-marker in steady position by bearing down withhisingers on the rounded triangular flanges at the extreme rear of the right and left arms. As he depresses the spring steel arms, the needle points, which protrude a small distance below the under surface of the transparent disks will pierce fine holes in the emulsion of the photograph. The operator continuously watches the fused dot while the photographs are being pierced, to assure that it remains in correct position and elevation. In this manner'he ,can check theaccuracy of his work at all times;

It will be obvious that in many instances a point -which has previously been marked on one photograph must be transferred to an overlapping photograph.Y In such case the stereo-marker is manipulated as described above until the fused dot -is in proper precise position and elevation. Then, however, instead of depressing both spring metal arms, theop'erator will only depress one arm, that one which is over the photograph to be marked. Since the point on the other photograph has previously been marked, its corresponding marker will not be depressed. Again, the operator can check the precision of' his marking as it is being done. Recapitulating, the invention is so designed that a point can .be marked on either the left photograph, or the right photograph, or both photographs simultaneously, .without changing the position of the instrument.

After one point has been transferred, the stereo-marker will be moved to position for transfer of the next selected point. Again that point can be transferred from the left photograph to the right photograph, from the right photograph to the leftphotograph, or can be simultaneously marked on both photographs at the will of the operator.

The point transfer will be effected from picture to overlapping picture either along the flight strip or between adjacent flight strips as the necessities of the work and the particular technical method of using the photographs dictate. As many points as are necessary, and in the locations where they are needed, can be transferred from picture to picture. While the floating dot is used infillustrating the operation of this invention, the mark may consist of some other geometric form such as a small circle, a small cross, or other suitable form.

The foregoing description is believed to be adequate to convey a clear. impression of how the device functions in the basic operation of transferring a point from one photograph to an overlapping one.' Of course, this basic operation will be repeated until sufficient points have been transferred to satisfy the technical demands for a project`of any given size or area, covering anywhere from two photographs to an unlimited number of photographs.

A more detailed description is given below of the useand operation of the stereo-marker with particular reference to the accompanying drawings in which like reference characters denote like parts, and in which:

Fig. 1 is a front View of the stereo-marker in proper position under a mirror-type stereoscope;

Fig. 2 is a side view ofthe stereo-marker and stereoscope in the same operating position as shown in Fig. 1;

' Fig. 3 is a perspective view of the stereo-marker and stereoscope and also showing two aerial photographsin'relative position for point transfer;

Fig; 4is atopplan view of the stereo-marker, partly insection and partly broken away;

kFig.,5V is a section 'of the device taken along line 5-5 of Fig. 4; and Y circular tube.

Fig 6 is a side view of the device in section taken along line 8-6 of Fig. 4.

Onthe left-hand arm I the fine needle-,point 2 is fastened in the lower surface of the rigid transparent disk 3. The top of this needle, as seen from above, is colored with a dye or pigment or other coloring matter so as to look like a small dot 4. The disk is supported in a circular frame 5 which in turn is supported in two grooved recesses 6 and can be moved longitudinally with respect to arm I by means of adjusting screw 1 which operates through a lug 8 fastened to collar 9. Collar 9 supports the recessed parts 6 and is rigidly fastened to spring arm I at its front end. At the back end spring arm I is rigidly fastened to vertical slide plate I. Slide plate I is held against the vertical face of housing II by means of retaining plate I2 and screws I3 in such a way that it can be moved vertically by means of adjustment screw I4 operating in a threaded lug I attached to the top of slide plate I0. Screw I4 is retained in proper position by screw I 6 bearing in a recess at the lower end of screw I4. The tension on screws I3 is such that the fit between slide plate I0 and housing II is a snug sliding fit.

Housing Il, by virtue of a circular bore I1, iits snugly on bar I8 and may be slid along to various positions on the bar. Housing I I is equipped with a clamp screw 4Iel which engages threads 20 in the housing and permits it to be rmly clamped to .bar I8 .in any desired position. Flange 2I at the rear of housing II is an integral part of the housing, and is to be used as a means of holding the stereo-marker in steady position by virtue of downward vertical pressure exerted on it by the operators fingers. Bar I8 is in the form of a The base 22 of housing II constitutes the base of the left part of the stereornarker and in operation it will rest either on the photograph or on the working surface which supports the photograph.

On the right-hand arm I' a ne needle-point 2', similar to needle point 2, is fastened in the lower side of rigid, transparent disk 3'. The top of this needle, as seen from above, is colored with a dye, or pigment, or .other lcoloring matter so as to look like a small dot 4. The disk is supported in a circular frame 5. The frame 5 is rigidly attached to the front end of spring-arm I. At the back end, spring arm I is rigidly fastened to verticalslide plate ID'. Slide plate I0 is held against the vertical face of housing II' by means of retaining plate I2' and screws I3' in such a way that it can be moved vertically by means of adjustment screw I4 operating in a threaded lug I5 attached to the top of slide plate I0'. Screw I4 is retained in proper position by screw I6' bearing in the recess at the lower end of screw I4.` The tension on screws I3' is such that the t between housing II and slide plate It' is -a'snug sliding fit. Housing II', by virtue of a circular bore I1', ts snugly on bar I8 near the right end thereof. Flange 2| at the rear end of housing I I is an integral part of the housing, and is to be used as a means of holding the stereo-marker in steady position by virtue of downward vertical pressure exerted on it by the operators fingers. The base 22' of housing II constitutes the base of the right part of the stereo-marker and in operation it will rest either on the photograph or on the working surface which supports the photograph.

Horizontal bar I8 is in the form of a hollow tube. At the right end there is a horizontal slot 23 in bar I8 to permit housing Il to be rigidly connected to nut 24 by means of plate 25, which is a flat strip of metal securely fastened in a slot in housing II' by means of screws 26 and 21. This fiat strip of metal is rigidly fastened at the other end to sliding nut 24. Nut 24 has an outer circular circumference of such size that it ts the inner circumference of bar I8 snugly. Adjustment screw 28 threads into sliding nut 24 and causes it to move longitudinally in either direction along the bar when properly rotated. Screw .28 is held in proper place by set screws 29 and 30 which operate in a recess in screw 28. A collar 3l, also held in place by set-screws 29 and 30, is provided to keep screw 28 in correct axial alignment.

From the foregoing detailed description of parts and members it will be clear that the distance along the bar I8 between housings II and Il can be varied by hand movement of the left housing until the approximate desired distance is obtained, and then a fine adjustment of this distance can be obtained by means of adjusting screw 28. The relative motion in this direction between dot 4 and dot 4' will be hereinafter referred to as the b-.r motion. Furthermore it will be clear that relative motion between dots 4 and 4 in a horizontal plane and at right angles to the axis of bar I8 can be effected by the use of adjusting screw 1. This relative movement will hereafter be referred to as the b-y motion. Also, it will be clear that relative or concurrent vertical motion of or between dots 4 and 4' can be effected by means of adjusting screws I4 and I4. This motion will be hereafter referred to as the b-z motion. Relative motion between the two dots, and consequently between the two needle-points 2 and 2', in these three cardinal directions is the necessary fundamental consideration to cause the fused dot, as seen through the stereoscope, to rest exactly on a point at the desired elevation. It is, of course, apparent that the whole instrument can be first shifted by hand to an approximate operating position before ne adjustments are made with the screws.

In normal operation, after the two overlapping aerial photographs have been properly positioned and oriented under or in a conventional mirrortype stereoscope generally designated at 32, the b-x distance between successive pairs of like points on the photographs will vary only by a small amount caused by differences in elevation. It is intended that the movement afforded by use of screw 28 will be suii'icient to cover the range of travel caused by normal elevation differences so that after the first point has been marked or transferred the remainder of the points on those same two photographs can be marked without loosening clamp screw I9. This feature will permit rapid b-:c distance adjustment in most cases by use of screw 28 alone.

Furthermore, unless the aerial photographs are severely tilted with respect to each other, imaginary lines passing through successive pairs of like points on the photographs will be approxim'ately parallel to each other. Accordingly, the line between dots 4 and 4 would, for settings on successive pairs of like points, assume approximately parallel positions. If the stereo-marker were rigidly fastened to any of the several types of drafting arms or parallel movement devices, it would, when moved about, automatically assume a position parallel to its initial position, and the necessary adjustment of the relative b--y motion between the dots 4 and 4' could be accomplished `7 throiiehuse of' enit# tnesciewi. sin# er an initialVsetti-lg was' made orithe common on two photographs; subsequent lne-y distance adjustments ori` successive pairsorpcintson the same two; priotograprlsl could rapidly be nra'de by means o'f Screw@r E The stereo-marker can bex` operated with the' bases of airges 2"I'= and 2li" resting either on the surface or the photographs orfon the sii-rifae'e which' supports the prio-togiraplis; since provision is made for a -ne adjustment a DLLs-direction or both needle-points 2 and 2'r with respect to eakzixA other and with`V respecty to the bases of@ the flanges 2f and 21". The needles can thus be ad'- .msted so* that the points wili not catch` on, or scratch the surfaces of the photographs asthe stero-marker is s-iiifteidc aboutl For this sP-iifft'ifng, theneedleepoilits are raisedgbysselews I1@ and f4" sucientlytoconvenientiy clear tHe-surface of the photographs. When a peint is being transferred the needle pointsA and- 2"` are lowered by" means of the screws ld and IW to-a level just" above the .sl'irfac'e oi the photographs. is most' desir- :a'ble forl precise` point transfer. Y

For' a more: detailed description of the modus operandi, seepage' 4, line` 16s'upra et sed. to page "i, line 3; e

From tli'e'r foregoing d'escriptioi'ir it` canA be seen "that" tljiis instrument is designed to accomplish the 'transfer' and marking` of points on aerial' photo graphs' with` utmost ,precision limited ,only bythe perceptive capabilities of tire human eyes. Its operation can easily be learned by an inexperie enc'ed. operator, and each' point' ofA transfer can 'beimmediately checked, ,bothk wht-ie and after being done; It isalso designed so that thel operation, can be accomplished'witli greater'vspeed and :facility than with other means employed in this 'highly technical' art. It is further to be understood. thatits use is to be considered adaptable to any stereoscopioA means of viewing aerial photograplis either with or' vwithout optical magnni'cation as a part of the stereoscope.

What' is' claimed:

1. Adevi'ce for Use iii constructing maps from aerial photograps and employing th'e'flioating, dot principle in operation, comprising a base, two adinstablearms associated Awith and extending from said base, and a transparent member' o'n each of saldarms carrying a small indicia dot andV coincident point marking means. 2; A device' for use in constructingmaps from aerial photographs and employing thel floating dot principle in operation", comprising' a base` consisting oi a bar and two spaced surface-engagirigmembers ongitudinallyslidable thereon, two adjdstable arms associated with and extending fromsaid surface-'engaging members and a transparent member on each of said arms carrying a small indicia dot andcoincident point marking means.

3'. A device for use in constructing` maps from aerial photographs and employing the 'oating dot'principle in operation, comprising a base consisting of a bar and two surface-engaging members iorigitiidi'nally slidable thereon, adjustable arms associated with and extending from each of saidl suriacengaging members, transparent members on said arms each carrying a small indleia dot and-coincident point markingvmean-s and meaiisfor vertical adjustment of said arms.

4f. A- devicev for use im constrweting maps aerial photographs.' andi employing; the: floating. doi-31 principie in operationY comprisinga baise consisting: oai' a, bar two: surface-engaging. membe longitudinally' sldable thereon, adinstazhle arms associated Witlir and? extending. at right angles to saidibar from; each or said surface-err gagin'g members.. transparent members at. the outer' endi or' eac'lr anni` carrying; a small: indicia dota. and neenlle-pointmarking means: coincident disposedimmediatelyb'eneathsaid dots;

5i Aidevicjev fer user constructing maps from aerial pirotngraplis. and; employing tire ioating dot principle in; operationY comprising? abase' con.- sistinzg: oi as bar and: two: surface-engaging memloers` longiitndina'llyA siidable thereon; adjustable arms associated with. and.: extending. atv right angles toi sairl bar from: each off said; surface en easing: members. transparent' members' at the outer ensty of: eacla: arm. carrying a; smal-l indicia dat', needle-poi=lrrt marking. means coincident-.With and. disposedt immediately' beneath said. dots, means for vertiealadjustment: ofJ said:v arms'J and' mxealns1ior adjusting. the distance between: the arms.

6. A device for use in constructing; maps from aerial. photographs; and: employing the oating dot principle in., operatioisr,A coinqslrisin'g` a base consisting: oiV a liarA and twor. surface-engaging mernber neitu'di'zi'ally slfdable thereon,..adiust abi-erre :lient larms associatedzwith.: and: extending at right-:anglesrosal-deber from each-.of said-sur.- iaeeeengagilg members, transparent members at theL Outer. endet each arm carrying asmall indiciadot, needle-point marking means coincident with` and disp'osedlimmediately-beneatir said dots; means-for vertical adjustment oisaid arms and means `for"adi,trs-,ting the; distance between the arms.

7. A- deviceior use ineonstructingmaps from aerial pho-toeraplisr and. employing the floating dot principle in operation, comprising. abase consist-ing of-afbara11dftwo surface-engaging; meinberslongitufdirrailiy slidable thereon, adjustable resilient arms' associatedwith and extending ai: rightangles` to said barftrem eachlof said surfaceengagingmembers, transparent members at the outer endfofv each arm carrying a small'indicia dot; needle-point marking :means coineideritw-ith and. disposed. immediately. `beneath said data; means for vertical adjustment of said. arms, mea-ns for adjusting the' distance between the armsaand mean-sion one-ofsaid-arms for adjust'- irig the distance.: between the dot; andthe bar.

EUGENE J; SCHLATTER;

REFERENCES irrenl The following references areof'record'in the iile of this patent:

UNITED STATES PATENTS 469,354 Germany ..-Y Dec. 8, 1928 

